Jan. 10, 2005
Dolores Beasley
Headquarters, Washington
(Phone: 202/358-1753)RELEASE: 05-012
HUBBLE'S INFRARED EYES HOME IN ON SUSPECTED EXTRASOLAR PLANET
NASA's Hubble Space Telescope (HST) is providing important supporting
evidence for the existence of a candidate planetary companion to a
relatively bright young brown dwarf star located 225 light-years away
in the southern constellation Hydra.
Astronomers at the European Southern Observatory's Very Large
Telescope (VLT) in Chile detected the planet candidate in April 2004.
They used infrared observations and adaptive optics to sharpen their
view. The VLT astronomers spotted a faint companion object to the
brown dwarf star 2MASSWJ 1207334-393254 (also known as 2M1207). The
object is a candidate planet, because it is only one-hundredth the
brightness of the brown dwarf (at the longer-than-Hubble wavelengths
observed with the VLT). It glimmers at barely 1800 degrees
Fahrenheit, which is cooler than a light bulb filament.
Since an extrasolar planet has never been directly imaged, this
remarkable observation required Hubble's unique abilities to do
follow-up observations to test and validate if it is indeed a planet.
Hubble's Near Infrared Camera and Multi-Object Spectrometer (NICMOS)
camera conducted complementary observations taken at shorter infrared
wavelength observations unobtainable from the ground. This wavelength
coverage is important, because it is needed to characterize the
object's physical nature.
Very high precision measurements of the relative position between the
dwarf and companion were obtained with NICMOS in August 2004. The
unique HST follow up observations were compared to the earlier VLT
observations to determine if the two objects are really
gravitationally bound and hence move across the sky together.
Astronomers said they can almost rule out the probability the
suspected planet is really a background object, since there was no
noticeable change in its position relative to the dwarf.
If the two objects are gravitationally bound, they are at least 5
billion miles apart, about 30 percent farther apart than Pluto and
the sun. Given the mass of 2M1207, inferred from its spectrum, the
companion object would take a sluggish 2,500 years to complete one
orbit. Any relative motion seen between the two on shorter time
scales would reveal the candidate planet as a background interloper,
not a gravitationally bound planet.
"The NICMOS photometry supports the conjecture the planet candidate is
about five times the mass of Jupiter if it indeed orbits the brown
dwarf," said Glenn Schneider of the University of Arizona, Tucson.
"The NICMOS position measurements, relative to VLT's, indicate the
object is a true (and thus orbiting) companion at a 99 percent level
of confidence. Further planned Hubble observations are required to
eliminate the one percent chance it is a coincidental background
object, which is not orbiting the dwarf," he added.
The candidate planet and dwarf are in the nearby TW Hydrae association
of young stars estimated to be less than 8 million years old. The HST
NICMOS observations found the object to be extremely red and
relatively much brighter at longer wavelengths. The colors match
theoretical expectations for an approximately 8 million-year-old
object that is about five times as massive as Jupiter. Further HST
observations by the NICMOS team are planned in April 2005. The HST is
a project of international cooperation between NASA and the European
Space Agency.
Schneider is presenting these Hubble observations today at the meeting
of the American Astronomical Society in San Diego, Calif.
Additional points of contact:
Ray Villard, Space Telescope Science Institute, Baltimore, (Phone:
410/338-4514)
Lori Stiles, University of Arizona, Tucson, (Phone: 520/626-4402)
Glenn Schneider, Steward Observatory, University of Arizona, (Phone:
520/621-5865)
Electronic image files and additional information are available on the
Internet at:
http://hubblesite.org/news/2005/03
&
http://nicmosis.as.arizona.edu:8000/AAS_JAN_2005/PR_11_14.html
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